Engine starter drive



Juiy 24, 1951 '.1. J. DIGBY 2,561.97?

ENGINE STARTER DRIVE v Filed Jan. 5o, 195o zsheets-sheee 1 x n u AORNE'Y July 24, 1951 J. J.- DIGBY 2,561,977

ENGINE STARTER DRIVE Filed Jan. 30, 1950 f 2 Sheet-s-Sheet/Z sa@ ,31 6o6246 a 41 zra 65 am mpz. l Bfwf l Patented July 24, 1951v *arem 1;starter:driveand more Aparticularlyfto a drive F'soffthe soa-.calledfanti-kiekout type which mainl. tains its mechanical, connection withthe engine .faslong as `the starting fmotor 'is energized'.

2' :f "Itisan object of the present-invention to pro-A f 'vide a Istarter drive fof the above-type Whichfis -.'eflicient andI quietinoperation, and simplein .gconstructionw I. f

V It `is'another objectcto tprovid'e" such a: dev/ieee.

Vwhich includes a positive typeof-'overrunning a? "clutch: connection,Tand means for causing the 'onriectionA 'to voverrun:'freely 'andquietly:

tisi'another object'to provide such adevice c fincorporatingineans forlimiting. the torque loads @transmittedthereby: :i f-r 'v1-.1 Iurtherilobjects `and advantages Willy be'ap- .E1-parent from thefollowingdescription taken in -sconnectio'nfwith the accompanyingdrawing in ,Whi'ch- Fig; '1 is :af-side elevation'v partly-broken awayand in section showing a preferred Vembodif'xment'of theinventionivvith" the parts: in idle'posi- -;ctFig.f.2-.is asimilarviewvshowing .they parts -in meshed pos ion-preparatoryto.crankingLop'era-- ,=tion;;;=f 1:..

Fig. 3 is a view similarito-fFig. 1 showing the parts in the positionassumed after the engine f. becomes self-operative, While the drive isstill?. ensergized; land` f' --":.Fig. 4 isa view similar to Fig. 1 ofasecond embodiment ofthe invention. I u In Fig. 1 of thefdravvingthereisv illustrated'a vpower shaft I onlwhich a 'screw shaft'2"is @anchoredby suitable means suolil as 'a cross'pin 3 retained therein byarthimble.

A control nut 5 Tisthreaded o'n'th'e screwy shaft HL2', and; a driving`coupling member-"6 having 'in- .inlined'driving'surfacesi'lf'is splinedon theconf't'rol' nut as indicated at 8, and normally rests'r :againstshoulders '9 -formedon the control nu't 5. I, HA'l pinionl I, isslidably'journalledv on the power haft I for ,longitudinal l,movementinto and 'out fof meshfwith a 'gear |2701l the engine to be started.

r'zAdriven overrunning clutch member' I 3 'is splinedg,

.ffonrthe pinion II as indicated'at I4, and av'lock tfring I5:seated'intheextended hubxIS yofthe pinion'I I' limits'the projection ofthe pinion from y thefdriven clutch member-:13. i 1 -v:LFA-transmission'sleeve member I'I is' arranged to connect 'the'driving coupling' member 6 to the driven clutch member I3, and-for 'thispurpose isfprovided 'with:tinclined'f'suriasces.J I 8 i adapted toaf'cooperatewith the inclined surfaces 1 of 'the drivfing-rcouplingzmemb'en'fandf wvithf driving O'Vrrun- .laseren 't rvlainesy Y2, I,

,. Aviation Corporation,- a cor-porationof` Deia-vf Ap lisation January30,1950, serial'Nmf14L295 f I' 'A 'I (cLvi-fvfr I A' i' ningclutch teethI9 arranged to. cooperate vvith similar teeth -20 on the drivenclutchimemberf f j A barrel member 2I surrounds-thevcouplingand 'clutch'members,- and a sleeve 22 is xedly mounted in one endthereofas by meansofa Washerg23 "and a retaining ange 24.` l-A second sleeve 25 is mountedon the transmission member I 'I within .the barrel and abuts at loneendr 'against theend lof the sleeve22. The 'other end ofthe sleeve ,'25

is flared outwardlytogform aradial flange "V26,

Iand a compression spring, 21 is located between the flange '26- anda'corresponding-iiangegZagn the transmission member IIf'I so .as-to`cooperate with the sleeves 22, to form;yielding thrust means urging'the-transmission member toward 'the driving coupling member 6,andtendingfito 1 'separatefthe overrunning clutch.members,I3v and :I1during high speed overrun of: thepinion and clutchfassembly I3land.I,I.AI

A heavy'shofrt compression fspring. here-shown inthe form o'ffa;pairrofjelastic, discs29j is'vintejrposed-'between'. the drivingcoupling member-and an internal shoulder 31 formed in; thev -.;barrel;so

las-to strongly resist movement-of the driving couplingf-m'ember '6toward-saidl shoulder. g i w An? anti-drift spring-32 is located intheyre need "portin33 offthe'barrel 2I'and-bears-vat one-:end against:anwinwardly extendingA iiange ,f 3l -atpthe "end-fof the 'barrel `and.at its f other :endl againsta.

radial shoulder 35 -gformedon :the thimble; 4. so thatthe spring 32forms-,yielding means for Withdrawingthe barrel yandits associatedparts-from Vn'iesh'ed position..` Airing 36 of ber or other suitablematerial is lseated on the reduced portion of the'ibarrel against theshoulden 3l', and is retained in position by aflockring315fwhile-fbeingfreeE torotateronfthe barrel. The= ringI is provvided with recesses' 'orw pockets V38 fadapted to; re- A"'ceive the'end of'aspring-pressedplunger 39 'connected Ato' the starting'switch whichcontrols vthe energization ofutl'le'drivefso` as to be projectedi'nt'o'ipositin to enter one ofsaidpocketswhenthe "drive isin meshedposition asf illustrated in A thrust bearing 4| in the'l form lofone-ormore annular 4thrust ring's isinterposed betweenithe end of thecontrol nut 5 anda shoulder 42 formed inthe interior vof`the'transm'ission memberfil'l. The transmission member is provided withaseoond thrustshoulderllS lo-eated'adjacent theiend f"of"the' pinion'II, and-'1 an 'abutment-ring Mf'is slidably" mounted-within lthetransmission lmeml' ber'lIfI; normally .seated-.against `the shoulder43. compression 'fsp'ringa 45 f in theA y'transmission member* ITIbears' atitsv rends' against; the :thrust bearing 4I and abutment ring44 so as to form therewith a yielding abutment for the pinion to resistits telescopic movement into the transmission member.

Means for yieldingly holding the driven overrunning clutch member I3 inengagement with the clutch teeth I9 of the transmission is provided inthe form of a light compression spring 46 located between the Washer 23and a flange 41 extending radially from said driven clutch member.

Centrifugal means for moving the driven clutch member out of engagementwith the transmission member when the pinion overruns the drive isprovided in the form of a plurality of balls 48 located in pockets 49 inthe driven clutch member I3 and arranged to cooperate with inclinedsurfaces 5I formed in lthe sleeve 22 so that when the balls moveradiallyLA outward by centrifugal ,force they serve to ca-m the drivenclutch member Yaway from the transmission member and ,hold the teeth I9,20 out of engagement.

In the Aoperation of this embodiment of the injgvention, and startingwith the parts in the posiy tions illustrated in Fig. 1, actuation ofthe `power 'shaft I by the starting motor, notillustrated, f'causes itto rotate in the direction of the arrow Qa,v` whereby the consequentrotation of the screw shaft 2 causes the nut 5 to be traversed to theright, which longitudinal movement is transmitted through the thrustbearing 4I to the transmiss'ion member I1; and -through the mesh en- "iorcir'ig spring 45 and thrust ring 44 to the pinion vl, causing it toenter into mesh with the engine earfl2 as shown in Fig. 2. Thelongitudinal *":inovement of the transmission member I1 islf'transmitted through the spring 21 and thrust sleeves 25, 22 to thebarrel member 2|, untilthe longitudinal movement 'of the assembly is ar-"refsted by engagement of the flange 34 of the 'v barrel againstv theadjacent end of fthe screw '"sliaft 2. Further rotation of the screwshaft "causesrotationof the driving coupling member "6',"`which causesthe inclined surfaces thereof to vcam the transmission member I1 to theright,

'compressing the spring 21 and also forcing to- "-'gether `theoverrunning clutch teeth I9, 20 after the spring 46 has been completelycompressed, as "illustrated in'Fig. 2. Thereafter, torque is trans-"mi'tted through the coupling and clutch members 'to the pinion to crankthe engine, excessive "shock'loads causing the inclinded surfaces 1, I8l of the coupling members to slide over each other so' as to yieldinglyprevent damage to the drive.

I When the engine starts, the rapid acceleration 'o'f the pinion IIby-the engine gear I2 causes "'clutch' teeth 20, I9 to overrun, whilethe transmission member I1 moves back a short distance until its travelis arrested by the plunger 39 engaging 'in pocket 3'8 of ring 36, asillustrated in Figj 3. If the engine continues self-operative, 'therapid rotation of the pinion I I causes the balls' 48 to move radiallyoutward and hold the overrunning clutch teeth I9, 20 out of engagementas shown inFig. 3 so -that the overrunning "-takes'place quietly andwithout excessive generationof heat. When the operator opens thestarting'switch, the plunger 39 is Withdrawn from engagement with thering 36, whereupon the drive `returns to idle position under the inuenceof the *anti-drift spring 32 and the overrunning action of the 4controlnut 5 on the screw shaft 2.

In the embodiment of the invention illustrated in Fig. 4 the parts aresubstantially the same as in'the first embodiment described, and aresimilarly numbered with the exception of lthe means for controlling thelongitudinal positions of the transmission and driven overrunning clutchmembers.

As there shown, the transmission member I1' has a flanged ring 60 fixedthereon, while the driven overrunning clutch member I3' is provided withcylindrical pockets 6I which are inclined to the axis of the drive, andslidably receive the centrifugal balls 48. When the balls move outwardlyunder the action of centrifugal force, they engage the flange 62 of thering 60 so as to move the driven clutch member I3 away from thetransmission member I1', compressing the clutch spring 46. The radialmovement of the balls 48' is limited by a thimble 63 mounted on theclutch member I3' and surrounding the pockets 6I and the flange 52 ofthe ring 60.

The operation of this embodiment of the invention is the same as thatpreviously described except fcr lthe fact that `the centrifugal balls inthis case act directly against the transmission member I1 instead ofagainst the thrust sleeve 22 connected `to the barrel 2I, thuspositively holding the corresponding clutch teeth of I1' and I 3 apartduring overrunning of the pinion and clutch assembly. The spring 21 andthrust sleeve 25 illustrated in the first embodiment of the inventionare thus rendered unnecessary, the function of the spring 21 beingperformed by the clutch spring 4S'.

A further advantage of this arrangement is that the balls 48' and thethimble 63' which limits the outward travel of the balls are bothattached to the clutch, hence they are rotating at the same speed duringoverrun and there is no relative movement between them with consequentabsence of friction, wear, and heat which would result if thimble andballs were moving relative to each other during overrun as in the designshown in Fig. 3.

Although two embodiments of the invention have been lshown and describedin detail, it will be understood that other embodiments are possible andchanges may be made in the design and arrangement of the parts Withoutdeparting from the spirit of the invention.

I claim:

1. In an engine starter drive a power shaft, a screw shaft iixedthereon, a control nut threaded on the screw shaft, a driving couplingmember having inclined torque-transmitting surfaces splined on thecontrol nut, a pinion slidably journalled on the power shaft forlongitudinal movement into and out of mesh with a gear of the engine tobe started, a. driven overrunning clutch member splined on the pinion, atransmission member comprising driven coupling means cooperating withthe driving coupling member and driving overrunning clutch meanscooperating with the driven clutch member; a barrel mem- Yber enclosingthe coupling and clutch members having an inturned shoulder, a spring inthe barrel bearing against said internal shoulder and the drivingcoupling member so as to force the latter against the transmissionmember, thrust means in the barrel limiting llongitudinal movement ofthe driven clutch member toward the engine gear including a compressionspring, and a thrust bearing transmitting the longitudinal movement ofthe control nut to the transmission member.

2.r An engine starter drive as set forth in claim l including further,abutment means mounted on the transmissionv member including a sleeveanchored to the barrel, and a springcooperatng with the abutment meansand the transmission member to urge the latter into engagement with thedriving coupling member.

3. An engine starter drive as .set forth in claim 2 including further,centrifugal means for moving the driven clutch member away from thetransmission member.

' 4. An engine starter drive as set forth in claim 2 in which thetransmission member is vprovided with an internal shoulder adjacent theend of the pinion, an abutment ring slidably mounted in the transmissionmember, a compression spring in the transmission member bearing at itsends against said thrust bearing and abutment ring, to form a yieldingabutment for the pinion and resist its telescopic movement into thetransmission member, and a lock member in the driven clutch memberlimiting the projection of the pinion therefrom.

5. An engine starter drive as set forth in claim 3 including further,means for limiting the travel of the barrel member toward the enginegear, yielding means for returning the barrel member to idle position,and means for preventing the return of the barrel member to idleposition during energization of the drive.

- JAMES J. DIGBY.

REFERENCES CITED The following references are of record in the iile ofthis patent:

UNITED STATES PATENTS Number Name Date 2,495,653 Digby Jan. 24, 1950

